计算表

Question

我有一个表allData

id     name       
1      meat
2      chicken
3      fish
4      chicken
5      fish
6      chicken     

和table relatedData

id        name
1         meat
2         fish

我想计算allData中每个名称的总发生次数，但仅限于relevantData中显示的名称。即 我想得到的结果：

id       name     count
1        meat     1
2        fish     2

我想到了查询：

Select count(*) from allData group by name

不确定我与relevantData的关联方式。有什么想法吗？

Answer 1

更改观点，您对relevantData感兴趣，这是您查询的基础。您可以使用相关子查询，无需使用join或group-by：

SELECT rd.name, 
       (SELECT COUNT(*) FROM allData ad WHERE rd.name = ad.name) AS Count
FROM relevantData rd

Demo

Answer 2

您可以尝试以下操作。

SELECT COUNT(*) FROM allData WHERE name in (SELECT name from relevantData) GROUP BY name

Answer 3

只需加入他们：

SELECT  a.id, a.name, COUNT(*) AS CntCol
FROM    allData a
        INNER JOIN relevantData r ON a.name = r.name
GROUP BY a.id, a.name

Answer 4

试试这个：

java -cp lucene-core-4.3.0.jar -ea:org.apache.lucene... org.apache.lucene.index.CheckIndex /opt/solr/cores/necc_db/index.20141215164500013


ERROR: could not read any segments file in directory
org.apache.lucene.index.CorruptIndexException: codec mismatch: actual codec=Lucene41NormsMetadata vs expected codec=segments (resource: ChecksumIndexInput(MMapIndexInput(path="/opt/solr/cores/necc_db/index.20141215164500013/segments_vilq")))
    at org.apache.lucene.codecs.CodecUtil.checkHeaderNoMagic(CodecUtil.java:140)
    at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:290)
    at org.apache.lucene.index.SegmentInfos$1.doBody(SegmentInfos.java:347)
    at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:783)
    at org.apache.lucene.index.SegmentInfos$FindSegmentsFile.run(SegmentInfos.java:630)
    at org.apache.lucene.index.SegmentInfos.read(SegmentInfos.java:343)
    at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:382)
    at org.apache.lucene.index.CheckIndex.main(CheckIndex.java:1854)

只需按ID分组，然后检查它是否包含在relatedData

中